This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primate TRIM5alpha protein mediates a potent, post-entry block to retroviral infection. We are studying the population-genetics of primate TRIM5alpha and using this knowledge to develop better models for HIV-1 replication and pathogenesis, and in ascertaining the effects of TRIM5alpha polymorphism on differential outcome during SIV infection.